1. Technical Field
The present invention relates to a metal powder production apparatus.
2. Related Art
There has been known a method for producing a metal powder using a so-called water atomization method (for example, see JP-A-2001-64703 (Patent Document 1)).
In the method for producing a metal powder described in Patent Document 1, a water atomization method is used as a liquid spraying method in which a liquid stream is sprayed on molten metal particles. In the water atomization method, a cooling speed after spraying is fast, and therefore, a molten metal is solidified before it is spheroidized by surface tension. Therefore, the obtained powder is likely to have an irregular shape.
With respect to such a problem, the invention described in Patent Document 1 has tried to solve the problem by adding a step of allowing a formed powder to pass through a region heated to a temperature equal to or higher than the melting point of the constituent metal of the powder to spheroidize the powder. The region heated to a temperature equal to or higher than the melting point refers to a plasma region or a combustion gas region.
However, in the method described in Patent Document 1, it is necessary to provide a plasma region or a combustion gas region, and therefore, an increase in the size of the apparatus or an increase in the cost cannot be avoided. Further, in this method, the metal powder once solidified is melted again, and therefore, an unintended change in the composition or crystal structure may be caused. In addition, for example, in the case where an amorphous metal powder is produced, unintended crystallization may be caused.